Cosplay / costume prop help needed

[puyaybusto]

For starters I know nothing about anything when it comes to the topic. I just happened to run across an item that I possibly can get a lot of and was wondering if people are out there looking for costume props. Basically it would be a gun but I would custom paint it and what not. I added an image below. Is there a market for these things? I tried searching on ebay but got nothing. To me I would say for like a Halo or Star wars type of costume. But someone who participates in these types of things would be helpful to tell me so I can know if it is worth messing around with. So any help let me know.

http://i47.photobucket.com/albums/f172/puyaybusto/Photo-0006.jpg?t=1236706731

Here's the item. The plastic on the bottom does move back and forth as if you were "cocking" it.